Recently, consciousness of a user about security has been enhanced. Accordingly, the trend has been increased wherein a user regards it a question that a sheet on which an image is formed by an image forming apparatus such as a copier and a printer is left in the image forming apparatus.
On the other hand, from the view point of resource saving, an image forming apparatus which forms an image on a sheet using erasable coloring material and erases the image of the sheet has been developed. After the sheet which a user has formed an image using the image forming apparatus becomes unnecessary, in order to reuse the sheet, a user can erase the image of the sheet by an erasing unit of the above-described image forming apparatus.
Furthermore, when it is determined that a security mark indicating that the sheet is a confidential document is formed on the sheet in the above-described image forming apparatus, the technology to erase the image of the sheet and dispose the sheet without reusing the sheet has been developed.
However, even with the above-described technology, the effect of countermeasure to the leaving of a sheet outputted from the image forming apparatus is insufficient.